# Relationship history for MSHA mine 2400500

Current hierarchy: **Howard D  Hamilton → Hamilton Sand & Gravel LLC → Blue Moon Pit**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Hamilton Enterprises Inc → Blue Moon Pit; 1950-01-01 to 1992-03-17; source msha-controller-operator-history
- **controller_controls_mine:** Howard D  Hamilton → Blue Moon Pit; 1950-01-01 to 1992-03-17; source msha-controller-operator-history
- **controller_controls_operator:** Howard D  Hamilton → Hamilton Enterprises Inc; 1950-01-01 to 1992-03-17; source msha-controller-operator-history
- **operator_operates_mine:** Maricorp Inc → Blue Moon Pit; 1992-03-18 to 1993-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Rick  Kratz et al → Blue Moon Pit; 1992-03-18 to 1993-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Rick  Kratz et al → Maricorp Inc; 1992-03-18 to 1993-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Whitefish Sand & Gravel → Blue Moon Pit; 1994-01-01 to 1995-06-14; source msha-controller-operator-history
- **controller_controls_mine:** John T  Ferguson → Blue Moon Pit; 1994-01-01 to 1995-06-14; source msha-controller-operator-history
- **controller_controls_operator:** John T  Ferguson → Whitefish Sand & Gravel; 1994-01-01 to 1995-06-14; source msha-controller-operator-history
- **operator_operates_mine:** Hamilton Rock Products LLC → Blue Moon Pit; 1995-06-15 to 2007-10-31; source msha-controller-operator-history
- **controller_controls_mine:** Howard D  Hamilton  et al → Blue Moon Pit; 1995-06-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Howard D  Hamilton  et al → Hamilton Rock Products LLC; 1995-06-15 to 2007-10-31; source msha-controller-operator-history
- **controller_controls_operator:** W E  Schreiber  et al → Hamilton Rock Products LLC; 1995-06-15 to 2007-10-31; source msha-controller-operator-history
- **operator_operates_mine:** Hamilton Sand & Gravel LLC → Blue Moon Pit; 2007-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Howard D  Hamilton → Blue Moon Pit; 2007-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Howard D  Hamilton → Hamilton Sand & Gravel LLC; 2007-11-01 to current/open; source msha-controller-operator-history